Field of the Invention
The invention relates to an in-ear headset module, more specifically relates to a passive noise-cancelling in-ear headset module.
Description of Related Art
Along with the continuous improvement of technology, all of electronic products have been developed with a tendency to become lighter and more miniaturized, and the electronic products like smartphone, tablet computer, or notebook, etc., have become indispensable in daily life of human beings. For each of those aforementioned electronic products, in order to allow a user/listener to listen to the audio information provided by the electronic product without disturbing the other people around, an earphone has become a necessary accessory to the electronic product. Moreover, the earphone also provides a better audio transmission to the listener so that the listener can clearly hear and understand the content of the audio information, and especially, unlike the an unclear audio transmission through the air, the audio transmission of the earphone is not be affected while the listener is moving, such as exercising, driving, engaging in intense movements or being in a noisy environment. Otherwise, in order to make a phone call by using the electronic products, a headset having a microphone is also a popular accessory.
In order to perform both audio listening and sound collecting functions, a conventional headset adopts a design having an earphone and a microphone separated from each other, the earphone and the microphone are connected to each other via a signal wire or a simple structure. Therefore, the earphone is close to the ear, and the microphone is close to the mouth. However, the microphone in the above-mentioned design also receives the environmental noise, so the distinctness of the voice of the user is greatly affected. If an active noise-cancelling method is adopted, a noise-cancelling circuit needs being installed so as to increase cost, and the fidelity of the collected sound is also damaged when using the active noise-cancelling method. Otherwise, in order to decrease the volume of the headset, another conventional headset adopts Bluetooth communication, and the earphone and the microphone are disposed inside the same casing. However, like the old design, the microphone of this design is located at an end closest to the mouth, and the distance between the microphone and the mouth becomes longer, so a more expensive directional microphone needs to be adopted to receive sound.